Evolution of mobile communications networks and emergence of applications with different communications features are accompanied with emergence of UEs of different communications types. Therefore, operators put forward a solution of separately deploying DCNs (Dedicated Core Network) for UE of different communications types. In the prior art, to avoid as much as possible a redirection or handover process from occurring when UE (User Equipment) accesses a DCN, the UE includes selection assistance information of the DCN in an RRC (Radio Resource Control) connection message sent to a RAN (Radio Access Network) node, to indicate a DCN that the UE requests to access. The RAN node is configured to control the UE to access a mobile communications network by means of radio access, so that the RAN node may select, for the UE according to the selection assistance information that is of the DCN and reported by the UE, a PLMN (Public Land Mobile Network) to which the accessed DCN belongs. In this way, the UE binds an identifier of a PLMN that serves the UE to the selection assistance information of the DCN delivered by the accessed DCN, that is, stores a correspondence between the two.
However, in a network sharing scenario, core networks of multiple operators share a shared RAN node. Even if the UE accesses the PLMN to which the DCN belongs, if the RAN node is a shared RAN node, when the shared RAN node broadcasts only an identifier of a common PLMN, or when the UE can obtain only a identifier of the common PLMN, the UE is actually bound to a correspondence between an identifier of a common PLMN and network selection assistance information. An identifier of a PLMN that serves the UE and that is actually accessed by the UE is different from the identifier of the common PLMN, and therefore, the UE cannot know the actually accessed PLMN. Consequently, when the UE moves from a range of the shared RAN node to a range of a RAN node exclusive to the actually accessed PLMN, the UE does not store a correspondence between the PLMN and selection assistance information of a DCN. Therefore, according to the existing solution, the UE needs to access a network by using selection assistance information of a default DCN, and the RAN node exclusive to the actually accessed PLMN re-selects an accessed DCN for the UE. Consequently, a redirection process for selecting a DCN caused, and resource overheads are increased.